These are all interesting for collaboration writing... and I think Scrivener and/or Novel Factory can help me in my long novels.

By the way, there's the program Inkle which is interactive-fiction game making tool and I find it so much interesting.... and I believe it can help a lot of writers to expand their writing.

I have an idea that includes this program for the fiction-workshop but I'm saving it until I become a better writer. (read: publish the story that always gets edits from our friends)